The invention concerns block polymers of poly-2-isopropenylnaphthalene and polybutadiene-1,3, and methods for their production.
It is already known that 2-isopropenylnaphthalene can be anionically polymerized in a solvent, such as for example tetrahydrofuran, in the presence a catalyst from the series of alkalimetals, alkalimetalalkyls,-aryls or -hydrides, at temperatures between 0.degree. and -80.degree. C. Depending on reaction conditions, homopolymerisates of different molecular weights can be so obtained. (Macromol. Chem. 62 (1963) p. 31.)
It is further known that one can obtain homopolymerisates of 2-isopropenylnapthalene, by reacting the monomer with alkalimetal-catalysts in an inert organic solvent, for example with sodium dispersed in benzene, at 3.degree. C. After termination of the reaction through the addition of methanol, homopolymers with a molecular weight of 100,000 and a softening range from 250.degree.-280.degree. C. are obtained. (U.S. Pat. No. 3,202,642.) It is moreover known to perform an anionic copolymerisation of 2-isopropenylnaphthalene with unsaturated compounds, for example styrene, under the same conditions.
Finally, it is also indeed known, that copolymers composed of 2 blocks are obtained when one allows n-butyllithium to act upon a solution of butadiene and styrene in aliphatic hydrocarbons. Herewith only the butadiene is reacted initially, and subsequently the styrene in added at the active chain end. The polymeric anion formed in the interim is characterized as a so-called "living" polymer. After termination of the reaction a copolymerisate is isolated, which displays structural blocks of poly-butadiene and poly-styrene. (Runge and Taeger, "Chemie und Technologie der Kunststoffe" Akademie-Verlag, Berlin 1976, page 478) In another manner a copolymer composed of 3 blocks can also be produced, by initially producing a poly-styrene block, adding to this a poly-butadiene block, and subsequently attaching a further poly-styrene block. This tri-block copolymer displayed already in unvulcanized condition at normal temperature, rubber/elastic characteristics.
A disadvantage of the known block polymers is the comparatively low high-temperature stability.